Once Upon a Time 5×12 “Souls of the Departed” – Emma, Regina, Mary Margaret, David, Robin, Henry and Gold arrive in the Underworld, on a mission to rescue Hook, only to discover that their search will be more difficult than they had anticipated. The inhabitants of the Underworld—all souls with unfinished business and many with quite personal vendettas—hound our heroes at every turn. Meanwhile, in an Enchanted Forest flashback, a familiar face from the Evil Queen’s past returns to present Regina with the perfect birthday gift, on the 100th episode of “Once Upon a Time,” Sunday, March 6th on ABC.